Colorectal cancer is the third most commonly diagnosed cancer in Canada. In 2019 in Canada, colorectal cancer made up 13% of cancer cases in males, and 11% of cancer cases in females. Rectal cancer is a subset of colorectal cancer, and symptoms include changes in bowel habits, rectal bleeding, and weight loss. The treatment of rectal cancer can be challenging as what works for one patient may not work for another, additionally the five year survival of patients with advanced rectal cancer is 58%. The location of rectal cancer is defined by its distance from the anal verge (i.e., the junction of the anal canal and the external skin); lower or distal cancers are four to eight centimetres from the anal verge, middle rectal cancers are eight to 12 centimetres, and upper or proximal cancers are 12 to 15 centimetres from the anal verge. Surgery is one of the main therapies for rectal cancer, with the primary goal being complete removal of the tumour. The stage, size, and location of the tumour, and the patient’s characteristics (e.g., sex, BMI, skeletal morphology) can affect the choice of surgical approach for rectal cancer. Total mesorectal excision (TME), which involves the complete removal of the rectum and surrounding lymphatic tissue, is the standard of care for tumours in the distal to middle rectum. TME can be performed with open or laparoscopic techniques. Laparoscopic TME (LaTME) can be complicated by certain factors, such as the patient’s pelvic anatomy (i.e., a narrow pelvis), or obesity, thus reducing the surgeon’s ability to access the distal part of the rectum. In such cases, a laparoscopic procedure would need to be converted to the more invasive open TME procedure, which may result in worse short-term post-surgical outcomes. Transanal endoscopic surgery is a technique that offers access to rectal cancers through the anus. Transanal total mesorectal excision (TaTME), is a surgical procedure that combines the transanal endoscopic surgery approach with the LaTME procedure. TaTME facilitates the surgical treatment for distal and middle rectal cancers; the distal part of the rectum can be reached through the transanal approach, and the tumours in the middle rectum can be reached laparoscopically. The TaTME approach is a minimally invasive surgery for rectal cancer, and may facilitate access to tumours that are not amenable to the laparoscopic approach (e.g., patients who are obese, patients who have a narrow pelvis). In some Canadian hospitals, both the TME and the transanal endoscopic surgery are regularly used for rectal cancer, however, the TaTME procedure which combines both approaches is not widely used. The purpose of the report is to review and critically appraise the evidence pertaining to the clinical effectiveness and the cost-effectiveness of the TaTME for adult patients with middle to distal rectal cancer compared to open and laparoscopic TME. This information may be use used to inform decision making relating to clinical practice for the use of TaTME.